Combustion engine with a forced recirculation mixer

Description

[0001] The present invention relates to a heat engine comprising a forced recirculation mixer essentially designed to mix at least one liquid and at least one gas in determined proportions, and over a wide mass flow range.

[0002] Said mixer according to the present invention is particularly suitable for the implementation of the valve ignition pre-chamber which was the subject of patent No. FR 3 061 743 published on August 16, 2019, said patent belonging to the applicant.

[0003] Said pre-chamber provides that a pilot charge is injected into a stratification cavity by a stratification injector, said charge being in the majority of cases and particularly in automobiles made up of an easily flammable air-gasoline mixture which has previously been put under pressure by compression means.

[0004] The invention according to patent FR 3 061 743 is in fact particularly intended for the automotive market. However, this market is very sensitive to the cost price, weight and size of any equipment, which must remain as low as possible. The automotive market is also very demanding in terms of robustness, reliability, lifespan and maintenance.

[0005] Some mixers are known for other applications such as US1668601A or US2010 / 196518A1, but are not intended for use with a pre-ignition chamber.

[0006] It is in this context that the ignition pre-chamber with valve according to patent FR 3 061 743 is placed, said pre-chamber requiring both great precision in the dosage of the air-fuel mixture which constitutes the pilot charge, and high quality in the preparation of said mixture which must be as homogeneous as possible.

[0007] However, the preparation of the said mixture takes place at a relatively high pressure of around forty or fifty bars, while the flow rate of the air with which the petrol must be mixed is very low, the said flow rate of air being able to vary in intensity by a factor of one hundred and fifty, or even more.

[0008] Furthermore, it is essential that the gasoline be completely vaporized into the air receiving it before introducing the resulting air-gasoline mixture into the stratification cavity by means of the stratification injector.

[0009] It is also essential to prevent any partial re-condensation of the gasoline despite the high pressure to which the air-gasoline mixture is subjected, said re-condensation being able to occur if the homogeneity of said mixture is insufficient.

[0010] Because in fact, the quality of combustion of the pilot charge in the stratification cavity depends both on its composition and in particular, on the air / fuel ratio of the mixture to be burned, and on its homogeneity.

[0011] It is therefore primarily to implement the ignition pre-chamber with valve according to patent FR 3 061 743 that, according to a particular embodiment, the forced recirculation mixer according to the invention: offers high precision in injecting gasoline into the air to precisely control the air / gasoline ratio of the resulting air-gasoline mixture, despite very low mass flow rates of gasoline involved, and despite a min / max flow range of air and gasoline to be covered which can go from one to one hundred and fifty, or even more; guarantees the complete vaporization of the gasoline in the air; guarantees a high homogeneity of the air-gasoline mixture, and the absence of any partial re-condensation of the gasoline; can operate over a wide temperature range, compatible with the constraints of the automobile engine; is insensitive to the vibrations produced by a thermal engine, said vibrations not affecting the measurement accuracy of said mixer; has durability, robustness and reliability compatible with the automobile; requires no special maintenance; is light and compact.

[0012] It is understood that the forced recirculation mixer according to the invention can not only be applied to the ignition pre-chamber with valve according to patent FR 3 061 743, but also to any other application, whatever the type or field, which requires mixing at least one gas with at least one liquid in precise proportions and in a homogeneous manner, and this, whatever said gas or said liquid.

[0013] The forced recirculation mixer according to the present invention is intended to mix at least one vaporizable liquid with at least one gas to be mixed so as to form a homogeneous gas mixture, said mixer comprising: At least one mixing chamber whose internal cavity forms a recirculation loop in which the homogeneous gas mixture can continuously circulate, the start and end of the recirculation loop being the same; At least one gas inlet duct which opens directly or indirectly into the mixing chamber and through which the gas to be mixed is introduced into the recirculation loop by means for introducing gas in a known quantity; At least one liquid injection nozzle which opens directly or indirectly into the mixing chamber to introduce the vaporizable liquid into the recirculation loop, said nozzle being supplied by means for introducing liquid in a controlled quantity, the flow rate of which is controlled by a computer, said vaporizable liquid forming, with the gas to be mixed, the homogeneous gas mixture;At least one mixing withdrawal conduit which opens directly or indirectly into the mixing chamber and through which the homogeneous gas mixture can be withdrawn from the recirculation loop by gas withdrawal means; At least one mixing turbine which is set in motion by a turbine motor and which is positioned in the recirculation loop, said turbine forcing the homogeneous gas mixture to circulate in said loop.

[0014] The forced recirculation mixer according to the present invention comprises at least one external coaxial conduit, each end of which is closed by a reversal termination, while at least one internal coaxial conduit is housed in the external coaxial conduit and a space is left for the homogeneous gas mixture to circulate, on the one hand, between each reversal termination and the internal coaxial conduit and, on the other hand, between the internal face of the external coaxial conduit and the external face of the internal coaxial conduit, the direction of circulation of the homogeneous gas mixture in the external coaxial conduit being opposite to the direction of circulation of said mixture in the internal coaxial conduit.

[0015] The forced recirculation mixer according to the present invention comprises a mixing turbine which is wholly or partly housed in one of the return terminations, the homogeneous gas mixture being drawn in through the center of said turbine via the internal coaxial conduit before being discharged to the periphery of said turbine via the space left between the internal face of the external coaxial conduit and the external face of the internal coaxial conduit.

[0016] The forced recirculation mixer according to the present invention comprises a reversing termination which houses the mixing turbine which has a hollow hemi-toroidal shape while blades which comprise the mixing turbine have a complementary projecting hemi-toroidal shape, a small clearance being left between said termination and said blades.

[0017] The forced recirculation mixer according to the present invention comprises a gas inlet conduit which passes through one of the return terminations to open into the internal coaxial conduit.

[0018] The forced recirculation mixer according to the present invention comprises a reversal termination crossed by the gas inlet duct which has a hollow hemi-toroidal shape from which said duct emerges.

[0019] The forced recirculation mixer according to the present invention comprises a liquid injection nozzle which opens into the gas inlet duct, or at the outlet thereof.

[0020] The forced recirculation mixer according to the present invention comprises an inner coaxial duct which is held in position in the outer coaxial duct by at least one stirring blade which radially connects said inner coaxial duct to said outer coaxial duct.

[0021] The forced recirculation mixer according to the present invention comprises an external coaxial conduit or any of its reversing terminations which is wholly or partly enveloped by a draw-off ring, the interior of the latter being connected to the interior of the external coaxial conduit by at least one radial draw-off orifice, the mixing draw-off conduit being connected to the mixing enclosure by means of said ring and said orifice.

[0022] The forced recirculation mixer according to the present invention comprises a mixing chamber which comprises heating or cooling means.

[0023] The forced recirculation mixer according to the present invention comprises a turbine motor which is an electric motor which comprises on the one hand, a rotor which is integral in rotation with the mixing turbine and which is enclosed in the mixing enclosure, and on the other hand, a stator which is placed outside said enclosure, magnetic fields produced by said stator being able to pass through the wall of the mixing enclosure to set the rotor in rotation.

[0024] The forced recirculation mixer according to the present invention comprises means for introducing liquid in a controlled quantity which consist of a piston liquid pump which comprises a pump casing, said pump also comprising at least one single or double-acting pump piston which, under the action of a piston actuator cooperating with movement control means, can move in translation in a pump cylinder to form at least one pump chamber of variable volume into which the vaporizable liquid can be introduced via an inlet valve, and from which said liquid can be expelled towards the liquid injection nozzle via a discharge valve.

[0025] The forced recirculation mixer according to the present invention comprises a piston actuator which is constituted by a rotary electric actuator motor secured to the pump casing, said motor being able to rotate in either direction to drive in rotation driving transmission means which are secured in translation to the pump casing and which cooperate with driven transmission means which are secured in translation to the pump piston, said driving transmission means reacting with said casing to move said driven transmission means in longitudinal translation.

[0026] The forced recirculation mixer according to the present invention comprises driving transmission means which are formed of a worm screw which rotates a worm wheel which has a wheel thread, while the driven transmission means are formed of a piston thread which cooperates with the wheel thread.

[0027] The forced recirculation mixer according to the present invention comprises a gas mass flow meter which measures, directly or indirectly, the mass flow rate of the gas to be mixed which circulates in the gas inlet conduit and / or the mass flow rate of the homogeneous gas mixture which circulates in the mixture withdrawal conduit.

[0028] The forced recirculation mixer according to the present invention comprises means for introducing liquid in a controlled quantity which are constituted by an impulse pump which comprises a single or double-acting impulse pump piston which, under the action of a pump solenoid actuator, can move in translation in an impulse pump cylinder with which il forms at least one variable volume pulse pump chamber into which the vaporizable liquid can be introduced via a pulse pump inlet valve, and from which said liquid can be expelled towards the liquid injection nozzle via a pulse pump discharge valve.

[0029] The forced recirculation mixer according to the present invention comprises a volume and / or mass flow rate of vaporizable liquid which is returned to the computer by a vaporizable liquid flow meter placed upstream or downstream of the means for introducing liquid in a controlled quantity.

[0030] The forced recirculation mixer according to the present invention comprises a vaporizable liquid flow meter which consists of a flow meter piston which can move in a sealed manner in a flow meter cylinder so as to form, on the one hand, an upstream flow meter chamber which is directly or indirectly connected to a pressure source, and on the other hand, a downstream flow meter chamber which is directly or indirectly connected to the liquid injection nozzle, the position of said piston in said cylinder being transmitted to the computer by a position sensor while a flow meter piston return spring tends to push the flow meter piston towards the upstream flow meter chamber.

[0031] The forced recirculation mixer according to the present invention comprises an upstream flow meter chamber which can be connected to the downstream flow meter chamber by a flow meter piston return valve.

[0032] The forced recirculation mixer according to the present invention comprises a flowmeter piston return valve which comprises a rotatable sealing plate which can be held pressed against a valve orifice by a valve solenoid actuator.

[0033] The forced recirculation mixer according to the present invention comprises a nozzle accumulator which is interposed between the means for introducing liquid in a controlled quantity and the liquid injection nozzle.

[0034] The forced recirculation mixer according to the present invention comprises a nozzle accumulator which comprises a nozzle accumulator piston which forms, with an accumulator cylinder, an accumulator chamber, said piston being pushed towards said chamber by an accumulator spring while the liquid injection nozzle is integral with said piston and passes through the latter from side to side in the direction of its length.

[0035] The following description, with reference to the attached drawings given as non-limiting examples, will enable a better understanding of the invention, the characteristics it presents, and the advantages it is likely to provide: [ Fig. 1 ] is a schematic sectional view of the forced recirculation mixer according to the invention, the mixing chamber of which comprises an external coaxial conduit, an internal coaxial conduit, and heating or cooling means, while the means for introducing liquid in a controlled quantity consist of a piston liquid pump whose double-acting pump piston moves in a pump cylinder under the action of a worm screw driven in rotation by a rotary electric actuator motor, a worm wheel, a wheel thread and a piston thread. Fig. 2] is a close-up schematic sectional view of the forced recirculation mixer according to the invention and according to the variant illustrated in figure 1 , arrows allowing to visualize the flows of gas to be mixed, vaporizable liquid, and homogeneous gas mixture. Fig. 3 ] is a close-up schematic sectional view of the forced recirculation mixer according to the invention and according to the variant illustrated in figure 1 , framed on the piston liquid pump, and which illustrates the operation of said pump when the rotary electric actuator motor turns the worm screw clockwise. Fig. 4 ] is a close-up schematic sectional view of the forced recirculation mixer according to the invention and according to the variant illustrated in figure 1, framed on the piston liquid pump, and which illustrates the operation of said pump when the rotary electric actuator motor turns the worm screw counterclockwise. Fig. 5 ] is a three-dimensional view of the forced recirculation mixer according to the invention and according to the variant illustrated in figure 1 . [ Fig. 6 ] is a three-dimensional sectional view of the forced recirculation mixer according to the invention and according to the variant illustrated in figure 1 , the top cover of the piston liquid pump being slightly raised to reveal the worm screw driven in rotation by the rotary electric actuator motor. Fig. 7] is a schematic diagram of the forced recirculation mixer according to the invention as it can be applied to a heat engine which receives the ignition pre-chamber with valve which is the subject of patent No. FR 3 061 743, the means for introducing liquid in a controlled quantity into said mixer being constituted by a pulse pump which cooperates with a vaporizable liquid flow meter in particular constituted by a flow meter piston whose position is transmitted to the computer by a position sensor. Fig. 8 ] is a three-dimensional sectional view of the forced recirculation mixer according to the invention, the means for introducing liquid in a controlled quantity of which consist of a pulse pump which cooperates with a vaporizable liquid flow meter, in particular consisting of a flow meter piston, the position of which is measured by a position sensor. Fig. 9] is a three-dimensional sectional view of the forced recirculation mixer according to the invention and according to the variant illustrated in figure 8 , said section showing in particular a normally open flowmeter piston return valve which can connect the upstream flowmeter chamber to the downstream flowmeter chamber. Fig. 10 ] is a schematic sectional view of the flowmeter piston return valve of the forced recirculation mixer according to the invention shown in figure 9 , said valve comprising an orientable sealing plate held pressed by a valve solenoid actuator on a valve orifice by means of a valve seal, said actuator pushing on said plate by means of an elastic connection notably formed of a closing holding spring and a stop pin. DESCRIPTION OF THE INVENTION :

[0036] It was shown in figures 1 to 6the forced recirculation mixer 1 according to the invention, various details of its components, its variants, and its accessories.

[0037] As clearly shown in the figure 2 , the forced recirculation mixer 1 is intended to mix at least one vaporizable liquid 2 with at least one gas to be mixed 3 so as to form a homogeneous gas mixture 4.

[0038] We see in figures 1 to 4 and in figure 6 that the forced recirculation mixer 1 according to the invention comprises at least one mixing chamber 5 whose internal cavity forms a recirculation loop 6 in which the homogeneous gas mixture 4 can continuously circulate, the start and the end of the recirculation loop 6 being the same.

[0039] THE figures 1 to 4 and the figure 6further show that the forced recirculation mixer 1 comprises at least one gas inlet conduit 7 which opens directly or indirectly into the mixing chamber 5, and through which the gas to be mixed 3 is introduced into the recirculation loop 6 by means for introducing gas in a known quantity 8 which may for example consist of a compressor 18 or a pressurized gas tank associated with a gas mass flow meter 46 as shown in figure 1 , these devices 18, 46 being known to those skilled in the art.

[0040] We notice in figures 1 to 4 and in figure 6that the forced recirculation mixer 1 according to the invention also comprises at least one liquid injection nozzle 9 which opens directly or indirectly into the mixing chamber 5 to introduce the vaporizable liquid 2 into the recirculation loop 6, said nozzle 9 being supplied by means for introducing liquid in a controlled quantity 10 whose flow rate of vaporizable liquid 2 is controlled by a computer 45, said vaporizable liquid 2 forming, with the gas to be mixed 3, the homogeneous gas mixture 4

[0041] It is noted that the liquid injection nozzle 9 may be an integral part of the means for introducing liquid in a controlled quantity 10, the latter being able for example to consist of an injector with electromagnetic, piezoelectric or electro-hydraulic control known per se, or even of a pump injector whose piston or pump membrane is actuated by a solenoid or a piezoelectric battery and whose injected quantity of vaporizable liquid 2 per unit of time is reasonably controllable.

[0042] In figures 1 to 6it has also been shown that the forced recirculation mixer 1 according to the invention comprises at least one mixture withdrawal conduit 11 which opens directly or indirectly into the mixing chamber 5 and through which the homogeneous gas mixture 4 can be withdrawn from the recirculation loop 6 by gas withdrawal means 12 which may for example consist of a stratification injector 20 supplying pilot charge 55 to a valve ignition pre-chamber 21 as described in patent FR 3 061 743 belonging to the applicant.

[0043] As illustrated in figures 1 , 2 And 6 , the forced recirculation mixer 1 according to the invention comprises at least one mixing turbine 13 which is set in motion by a turbine motor 28 and which is positioned in the recirculation loop 6, said turbine 13 forcing the homogeneous gas mixture 4 to circulate in said loop 6.

[0044] Note that, as shown in figures 1 , 2 And 6 , the turbine motor 28 may be an electric motor 29. Alternatively, said motor 28 may be pneumatic, hydraulic, thermal or of any type known to those skilled in the art, whether said motor 28 is directly connected to the mixing turbine 13 to set it in motion, or indirectly connected to said turbine 13 by any type of transmission whatsoever.

[0045] As illustrated by the figures 1 , 2 And 6, the mixing enclosure 5 may comprise at least one external coaxial conduit 14, each end of which is closed by a reversal termination 15, while at least one internal coaxial conduit 16 is housed in the external coaxial conduit 14 and a space is left for the homogeneous gas mixture 4 to circulate, on the one hand, between each reversal termination 15 and the internal coaxial conduit 16 and, on the other hand, between the internal face of the external coaxial conduit 14 and the external face of the internal coaxial conduit 16, the direction of circulation of the homogeneous gas mixture 4 in the external coaxial conduit 14 being opposite to the direction of circulation of said mixture 4 in the internal coaxial conduit 16.

[0046] We also notice in figures 1 , 2 And 6that the mixing turbine 13 can be housed in whole or in part in one of the reversal terminations 15, the homogeneous gas mixture 4 being in this case sucked in by the center of said turbine 13 via the internal coaxial conduit 16 before being discharged to the periphery of said turbine 13 via the space left between the internal face of the external coaxial conduit 14 and the external face of the internal coaxial conduit 16.

[0047] THE figures 1 , 2 And 6 also show that the reversing termination 15 which houses the mixing turbine 13 can have a hollow hemi-toroidal shape while the blades 17 which the mixing turbine 13 comprises have a complementary projecting hemi-toroidal shape, a small clearance being left between said termination 15 and said blades 17.

[0048] As an alternative embodiment of the forced recirculation mixer 1 according to the invention shown in figures 1 to 4 and in figure 6, the gas inlet duct 7 can pass through one of the reversal terminations 15 to open into the internal coaxial duct 16.

[0049] In this case, the reversal termination 15 crossed by the gas intake duct 7 may have a hollow hemi-toroidal shape from which said duct 7 emerges.

[0050] In figures 1 to 4 and in figure 6 , it will be noted that advantageously the liquid injection nozzle 9 can open inside the gas inlet duct 7, or at the outlet of the latter. It will also be noted in said figures that to promote the vaporization of the vaporizable liquid 2, the gas inlet duct 7 and / or the internal coaxial duct 16 can take the form of a Venturi tube.

[0051] As shown by the figures 1 to 4 and the figure 6, the internal coaxial conduit 16 can be held fixedly in position in the external coaxial conduit 14 by at least one stirring vane 22 which radially connects said internal coaxial conduit 16 to said external coaxial conduit 14.

[0052] We also note that, as shown in figures 1 to 4 and in figure 6 , the mixing blade 22 can advantageously be designed to create turbulence and differences in speed or advancement in the flow of homogeneous gas mixture 4, so as to promote the homogeneity of the latter.

[0053] THE figures 1 to 4 and the figure 6illustrate that according to a particular embodiment of the forced recirculation mixer 1 according to the invention, the external coaxial conduit 14 or any one of its reversing terminations 15 can be entirely or partly surrounded by a draw-off ring 23, the interior of the latter being connected to the interior of the external coaxial conduit 14 by at least one radial draw-off orifice 24, the mixing draw-off conduit 11 being connected to the mixing enclosure 5 via said ring 23 and said orifice 24.

[0054] As can be seen in figures 1 to 4 and in figure 6, the shape and / or the position of the radial withdrawal orifice 24 may be provided to disturb as little as possible the flow of the gas to be mixed 3 in the external coaxial conduit 14. In this respect, the radial withdrawal orifice 24 may for example form a scoop which opens into the withdrawal ring 23, the outlet of said scoop forcing the withdrawn gas to be mixed 3 to turn around when it passes through said orifice 24.

[0055] In figures 1 to 4 and in figure 6 , it has also been shown that the mixing enclosure 5 can comprise heating or cooling means 25 which can be for example constituted by a thermal regulation chamber 26 as shown in said figures, said regulation chamber 26 surrounding all or part of said enclosure 5 while a heat transfer or refrigerant liquid or gas 27 circulates in said chamber 26.

[0056] As an alternative shown in figure 7, the heating or cooling means 25 may consist of at least one electrical heating resistor 62, or any other means known to those skilled in the art making it possible to supply or remove heat from the brewing enclosure 5.

[0057] It was shown in figures 1 , 2 And 6 that the turbine motor 28 can be an electric motor 29 which comprises on the one hand, a rotor 30 which is integral in rotation with the mixing turbine 13 and which is enclosed in the mixing enclosure 5, and on the other hand, a stator 31 which is placed outside said enclosure 5, magnetic fields produced by said stator 31 being able to pass through the wall of the mixing enclosure 5 to set the rotor 30 in rotation.

[0058] It is noted that according to this particular configuration of the forced recirculation mixer 1 according to the invention, the wall of the mixing enclosure 5 can advantageously be made of a non-magnetic material such as stainless steel, aluminum, or brass.

[0059] We see in figure 1 and in figures 3 to 6that the means for introducing liquid in controlled quantity 10 may consist of a piston liquid pump 32 which comprises a pump casing 42, said pump 32 also comprising at least one single- or double-acting pump piston 33 which, under the action of a piston actuator 34 cooperating with movement control means 44, can move in translation in a pump cylinder 35 to form at least one pump chamber 36 of variable volume into which the vaporizable liquid 2 can be introduced via an inlet valve 37, and from which said liquid 2 can be expelled towards the liquid injection nozzle 9 via a discharge valve 38.

[0060] It will be noted that the movement control means 44 may for example consist of an angular or linear, optical or “Hall effect” encoder, absolute or incremental, or consist of the step-by-step control of one or more linear or rotary electric motors, said control means 44 in all cases allowing a computer 45 to control the position and the speed of advancement of the pump piston 33 in the pump cylinder 35 and therefore, to control the quantity of vaporizable liquid 2 introduced into the recirculation loop 6 per unit of time.

[0061] It will also be noted that the pump piston 33 may include a piston seal 19 made for example of elastomer, said seal 19 being able to be simple, or composite and consisting of an O-ring which cooperates with a ring made of PTFE loaded with anti-abrasive and / or anti-friction particles.

[0062] We will notice in figure 1 and in figures 3 to 6that the piston actuator 34 may consist of a rotary electric actuator motor 39 secured to the pump casing 42, said motor 39 being able to rotate in either direction to drive in rotation driving transmission means 40 which are secured in translation to the pump casing 42 and which cooperate with driven transmission means 41 which are secured in translation to the pump piston 33, said driving transmission means 40 reacting with said casing 42 to move said driven transmission means 41 in longitudinal translation.

[0063] It will also be noted that the driving transmission means 40 may for example consist of a wheel which is tapped in its center and which is connected to the rotary electric actuator motor 39 by means of a reducer formed from a cascade of pinions, an epicyclic gear train, a succession of toothed pulleys and toothed belts, or any other type of reducer known to those skilled in the art, said wheel cooperating with a threaded rod which is integral in translation with the pump piston 33 and which forms the driven transmission means 41.

[0064] It will also be noted that the driving transmission means 40 and the driven transmission means 41 may be replaced by any other mechanism producing an equivalent or similar effect such as a rack and pinion gear device, or a pulley and cable device.

[0065] As shown by the figures 1 , 3 , 4 And 6and according to a particular embodiment of the forced recirculation mixer 1 according to the invention, the driving transmission means 40 can be formed of a worm 47 which drives in rotation a worm wheel 43 which has a wheel thread 56, while the driven transmission means 41 can be constituted of a piston thread 57 which cooperates with the wheel thread 56.

[0066] As illustrated in figure 1, a gas mass flow meter 46 can measure, directly or indirectly, the mass flow rate of the gas to be mixed 3 which circulates in the gas inlet duct 7 and / or the mass flow rate of the homogeneous gas mixture 4 which circulates in the mixture withdrawal duct 11, said flow meter 46 allowing the computer 16 to determine the mass flow rate of the vaporizable liquid 2 to be introduced into the mixing enclosure 5 by the liquid injection nozzle 9 to form in said enclosure 5 a homogeneous gas mixture 4 composed of vaporizable liquid 2 and gas to be mixed 3 in the desired proportions.

[0067] Once the mass flow rate of the vaporizable liquid 2 to be introduced into the mixing chamber 5 is determined, the computer 16 can control the means for introducing liquid in controlled quantity 10 so that the latter deliver to the liquid injection nozzle 9 the mass flow rate of vaporizable liquid 2 necessary for the formation of the homogeneous gas mixture 4 sought in the mixing chamber 5.

[0068] THE figures 7 to 9 show that the means for introducing liquid in controlled quantity 10 can consist of an impulse pump 63 which comprises a single or double-acting impulse pump piston 64 which, under the action of a pump solenoid actuator 65, can move in translation in an impulse pump cylinder 67.

[0069] In this case, the pulse pump piston 64 can form with the pulse pump cylinder 67 at least one pulse pump chamber 68 of variable volume into which the vaporizable liquid 2 can be introduced via a pulse pump inlet valve 69, and from which said liquid 2 can be expelled towards the liquid injection nozzle 9 via a pulse pump discharge valve 70.

[0070] In figures 7 to 9 , it has also been shown that the volume and / or mass flow rate of vaporizable liquid 2 can be returned to the computer 45 by a vaporizable liquid flow meter 71 placed upstream or downstream of the means for introducing liquid in controlled quantity 10.

[0071] According to this particular configuration of the forced recirculation mixer 1 according to the invention, the vaporizable liquid flow meter 71 can consist of a flow meter piston 72 which can move in a sealed manner in a flow meter cylinder 73 so as to form an upstream flow meter chamber 75 which is directly or indirectly connected to a pressure source 77, the latter being able to consist of the fuel pump 53 of a heat engine 51 which in parallel supplies the injectors known per se of said engine 51.

[0072] In this case, the flow meter piston 72 also forms with the flow meter cylinder 73 a downstream flow meter chamber 76 which is directly or indirectly connected to the liquid injection nozzle 9.

[0073] Still according to this particular configuration of the forced recirculation mixer 1 according to the invention, the position of the flow meter piston 72 in the flow meter cylinder 73 is transmitted to the computer 45 by a position sensor 74 which can be inductive, capacitive, optical or of any type known to those skilled in the art, while a flow meter piston return spring 78 tends to push the flow meter piston 72 towards the upstream flow meter chamber 75.

[0074] As we can clearly see in figures 7 And 10 , the upstream flow meter chamber 75 can be connected to the downstream flow meter chamber 76 by a flow meter piston return valve 72.

[0075] In this case, vaporizable liquid 2 is transferred from the upstream flow meter chamber 75 to the downstream flow meter chamber 76, this transfer resulting from the force exerted by the flow meter piston return spring 78 on the flow meter piston 72 which has the effect of moving the latter in the direction of the upstream flow meter chamber 75.

[0076] It is noted that the flowmeter piston return valve 72 may be of the "normally open" type as shown in figures 7 , 9 And 10 , or of the “normally closed” type.

[0077] There figure 10shows a particular embodiment of the flowmeter piston return valve 72 of the forced recirculation mixer 1 according to the invention according to which said valve 72 comprises an orientable sealing plate 85 which can be kept pressed against a valve orifice 86 by a valve solenoid actuator 88, while a valve seal 87 is interposed between said plate 85 and said orifice 86, and while the valve solenoid actuator 88 pushes on the orientable sealing plate 85 by means of an elastic connection 89.

[0078] As another alternative embodiment of the forced recirculation mixer 1 according to the invention, it has been shown in figures 7 to 9that a nozzle accumulator 80 can be interposed between the means for introducing liquid in controlled quantity 10 and the liquid injection nozzle 9 so that if said means 10 produce large variations in the flow rate of vaporizable liquid 2, the effective flow rate of said liquid 2 ejected by the liquid injection nozzle 9 into the mixing enclosure 5 is subject to said variations over a lesser amplitude.

[0079] In this case, the nozzle accumulator 80 may comprise a nozzle accumulator piston 81 which forms, with an accumulator cylinder 82, an accumulator chamber 83, said piston 81 being pushed towards said chamber 83 by an accumulator spring 84 while the liquid injection nozzle 9 is integral with said piston 81 and passes through the latter from side to side in the direction of its length. HOW THE INVENTION WORKS :

[0080] The operation of the forced recirculation mixer 1 according to the present invention is easily understood in view of the figures 1 to 6 .

[0081] To illustrate this operation, let us assume here that, as shown schematically in the figure 1 , the forced recirculation mixer 1 is used to supply a homogeneous gas mixture 4 to a stratification injector 20 provided for a valve ignition pre-chamber 21 as described in patent FR 3 061 743, said pre-chamber 21 being applied to a heat engine 51 responsible for propelling an automobile (not shown).

[0082] As seen in figures 1 And 7, the forced recirculation mixer 1 according to the invention advantageously replaces a carburetor or injector which would be placed at the inlet of the compressor 18. Compared to such a configuration, said mixer 1 eliminates any risk of self-ignition of the homogeneous gas mixture 4 in said compressor 18, and any risk of re-condensation inside said compressor 18 of the vaporizable liquid 2 which partly constitutes said mixture 4.

[0083] Furthermore, and compared to a carburetor or injector placed at the inlet of the compressor 18, the forced recirculation mixer 1 according to the invention prepares a homogeneous gas mixture 4 of more precise composition, of greater homogeneity, and potentially reduces the quantity of homogeneous gas mixture 4 stored between the inlet of the compressor 18 and the stratification injector 20.

[0084] the mixer 1 according to the invention also ensures permanent mixing of the homogeneous gas mixture 4 even when the thermal engine 51 is momentarily stopped, which is desirable for example in the context of hybrid thermal-electric applications such as those found in automobiles.

[0085] In this respect, the forced recirculation mixer 1 according to the invention leaves greater freedom to the technical definition of the compressor 18 than a carburetor or injector placed at the inlet of said compressor 18.

[0086] The fact remains that a carburetor or injector remains a possible solution for implementing the valve ignition pre-chamber 21 on any thermal engine 51, particularly if said engine is fitted to a mass-produced automobile.

[0087] In the context of the particular application of the forced recirculation mixer 1 according to the invention presented here, the homogeneous gas mixture 4 constitutes the pilot charge 55 which the stratification injector 20 introduces into the ignition pre-chamber with valve 21 at each cycle of the heat engine 51.

[0088] According to this particular example of implementation of the forced recirculation mixer 1 according to the invention, the stratification injector 20 and the ignition pre-chamber with valve 21 therefore form gas withdrawal means 12.

[0089] We will assume here that the gas to be mixed 3 is atmospheric air 49 while the vaporizable liquid 2 is gasoline 50 as commonly consumed by automobiles.

[0090] Let us also assume here that the homogeneous gas mixture 4 which feeds the stratification injector 20 must be composed, by way of non-limiting example, of fourteen grams of air 49 per gram of gasoline 50, said gas mixture 4 therefore being slightly rich compared to the stoichiometry.

[0091] Let us consider that in the context of this particular application of the forced recirculation mixer 1 according to the invention, the mass flow rate of homogeneous gas mixture 4 to be supplied to the stratification injector 20 when the heat engine 51 is idling is one hundred and fifty times lower than the mass flow rate of said mixture 4 to be supplied to said injector 20 when said engine 51 is operating at full power.

[0092] Let us consider here that whatever the operating point of the heat engine 51, the mass proportion of air 49 and gasoline 50 of which the homogeneous gas mixture 4 is made up must not vary.

[0093] Let us also assume that the homogeneous gas mixture 4 consisting of air 49 and gasoline 50 is supplied to the stratification injector 20 under a pressure of forty bars.

[0094] To achieve this result, we note in figure 1 that the air 49 is pressurized by the compressor 18 which is represented symbolically. Said compressor 18 cooperates with a gas mass flow meter 46. Together, said compressor 18 and said flow meter 46 form the means for introducing gas in known quantity 8 which comprises the forced recirculation mixer 1 according to the invention.

[0095] As a non-limiting example of an embodiment of said mixer 1, the figure 1 and the figures 3 to 6 show that the gasoline 50 is pressurized by a piston liquid pump 32 which includes a double-acting pump piston 33 which can move in translation in a pump cylinder 35 to form two pump chambers 36 of variable volume.

[0096] In figures 3 And 4 , arrows show that gasoline 50 is introduced into each of the pump chambers 36 via an inlet valve 37, said gasoline 50 then being expelled towards the liquid injection nozzle 9 via a discharge valve 38.

[0097] Thus constituted, the piston liquid pump 32 forms the means for introducing liquid in controlled quantity 10.

[0098] We note in figure 1 that the gasoline 50 comes from a gasoline tank 52 which includes the automobile powered by the thermal engine 51. We also note in figure 1 that, prior to its introduction into the piston liquid pump 32, the gasoline 50 is pressurized by a gasoline pump 53 also responsible for supplying a main injection system (not shown) which comprises said engine 51.

[0099] To produce a homogeneous gas mixture 4 in a proportion of fourteen grams of air 49 per gram of gasoline 50 under a pressure of forty bars, the mixing chamber 5 in which said mixture 4 is produced must be brought to a temperature of at least seventy degrees Celsius.

[0100] Said temperature is necessary for all of the gasoline 50 which forms the homogeneous gas mixture 4 to pass into the vapor state and remain in said state, taking into account the saturated vapor pressure of said gasoline 50 at said temperature.

[0101] This is why it has been planned, as shown by the figures 1 to 4 and the figure 6, a thermal regulation chamber 26 which surrounds a large part of the mixing enclosure 5. A heat transfer or refrigerant liquid or gas 27, consisting in this case of the cooling water 54 of the heat engine 51, circulates in the thermal regulation chamber 26. Said water 54 which circulates in the thermal regulation chamber 26 at a temperature close to one hundred degrees Celsius is symbolized in figure 2 by the letter “C”,

[0102] Thus, the thermal regulation chamber 26 constitutes heating or cooling means 25 which guarantee that the gasoline 50 from which the homogeneous gas mixture 4 is partly formed remains entirely in the vapor state, despite the pressure of forty bars to which said mixture 4 is subjected.

[0103] When the thermal engine 51 is idling, the total quantity of homogeneous gas mixture 4 introduced each second into the ignition pre-chamber with valve 21 by the stratification injector 20 is very small. In order of magnitude, said quantity can be twenty-two standard cubic centimeters of air 49 mixed with two point five cubic millimeters of gasoline 50.

[0104] Also, to obtain a homogeneous mixture of air 49 and gasoline 50, the homogeneous gas mixture 4 is stirred in the recirculation loop 6 which forms the internal cavity of the stirring enclosure 5.

[0105] Let us assume here that the mixing chamber 5 contains sixty cubic centimeters of homogeneous gas mixture 4 subjected to a pressure of forty bars. This quantity of said mixture 4 is that which the stratification injector 20 supplies each minute to the ignition pre-chamber with valve 21 in the form of pilot charges 55 when the thermal engine 51 is operating at idle.

[0106] When the heat engine 51 is idling, the mass flow rate of homogeneous gas mixture 4 circulating in the recirculation loop 6 is thus several tens to several hundreds of times greater than the flow rate of said mixture 4 drawn from the mixing chamber 5 by the stratification injector 20 to supply the ignition pre-chamber with valve 21.

[0107] The current homogeneous gas mixture 4 contained in the mixing chamber 5 and the mixing of said mixture 4 produced by its incessant movement in the recirculation loop 6 makes it possible to average the composition of said mixture 4 over a long period of time, and to make said mixture 4 highly homogeneous.

[0108] The mixing of the homogeneous gas mixture 4 is particularly illustrated in figure 2where it can be seen that the recirculation loop 6 is formed of an external coaxial conduit 14, each end of which is closed by a hollow hemi-toroidal shaped reversal termination 15, while an internal coaxial conduit 16 is housed in the external coaxial conduit 14 and a space is left for the homogeneous gas mixture 4 to circulate on the one hand, between each reversal termination 15 and the internal coaxial conduit 16 and on the other hand, between the internal face of the external coaxial conduit 14 and the external face of the internal coaxial conduit 16.

[0109] We notice in figure 2 that the direction of circulation of the homogeneous gas mixture 4 in the external coaxial conduit 14 is opposite to the direction of circulation of said mixture 4 in the internal coaxial conduit 16.

[0110] In figures 1 , 2 And 6, the mixing turbine 13 has been shown, which is partly housed in one of the reversal terminations 15, the homogeneous gas mixture 4 being sucked in through the center of said turbine 13 via the internal coaxial conduit 16 as illustrated particularly clearly by the arrows shown in figure 2 , this before being pushed back to the periphery of said turbine 13 via the space left between the internal face of the external coaxial conduit 14 and the external face of the internal coaxial conduit 16.

[0111] In figures 1 , 2 And 6 , it has been shown that advantageously and according to this example of embodiment of the forced recirculation mixer 1 according to the invention, the hollow hemi-toroidal shape of the reversing termination 15 which houses the mixing turbine 13 is complementary to the projecting shape of the blades 17 which comprises said turbine 13, a small clearance being left between said termination 15 and said blades 17.

[0112] We note in figure 1 that the turbine motor 28 which drives the mixing turbine 13 in rotation is an electric motor 29 which comprises on the one hand, a rotor 30 which is integral in rotation with the mixing turbine 13 and which is enclosed in the mixing enclosure 5, and on the other hand, a stator 31 which is placed outside said enclosure 5, rotating magnetic fields produced by said stator 31 passing through the wall of the mixing enclosure 5 to set the rotor 30 in rotation.

[0113] This particular configuration of the turbine motor 28 avoids having to resort to sealing a rotating shaft passing through the wall of the mixing enclosure 5 to ensure the rotational drive of the mixing turbine 13, which is advantageous given the relatively high pressure of forty bars prevailing in said enclosure 5.

[0114] We notice in figures 1 to 4 and in figure 6that to open into the internal coaxial conduit 16, the gas inlet conduit 7 passes through the reversal termination 15 opposite that which houses the mixing turbine 13.

[0115] As we can clearly see in figures 1 , 2 And 6 , the internal coaxial conduit 16 is held in position in the external coaxial conduit 14 by stirring vanes 22 which radially connect said internal coaxial conduit 16 to said external coaxial conduit 14. Advantageously, the stirring vanes 22 create turbulence and speed differences in the flow of homogeneous gas mixture 4, and promote the homogeneity of the latter.

[0116] As seen in figure 2, the gas to be mixed 3, here consisting of air 49 symbolized by the letter “A”, is introduced into the mixing chamber 5 via the gas inlet duct 7, while the liquid injection nozzle 9 opens into said duct 7 in the vicinity of the outlet of the latter into the mixing chamber 5.

[0117] The liquid injection nozzle 9 introduces into the air 49 circulating in the gas intake duct 7 the necessary quantity of vaporizable liquid 2 consisting here of gasoline 50 symbolized by the letter "F", so that a more or less homogeneous gas mixture 4 is formed, containing more or less gasoline 50 in the liquid state, this in a proportion of fourteen grams of air 49 per gram of gasoline 50.

[0118] Thus, the air 49 is pre-mixed with the gasoline 50, a part of which evaporates in the gas intake duct 7, the resulting gas mixture then emerging in the mixing chamber 5.

[0119] The premixture of air 49 and gasoline 50 thus formed is then driven into motion in the recirculation loop 6 by the homogeneous gas mixture 4 which is already circulating therein. Said premixture is then stirred in particular by the stirring turbine 13 and by the stirring blades 22, the gasoline 50 which constitutes said premixture evaporating entirely to form the desired homogeneous gas mixture 4.

[0120] It is noted that if a portion of the gasoline 50 leaves the gas intake duct 7 in the liquid state, it will inevitably be deposited on the surface of the blades 17 of the mixing turbine 13, on the internal or external face of the internal coaxial duct 16, on the internal face of the external coaxial duct 14, or on the surface of the mixing vanes 22. Then, the forced circulation of the homogeneous gas mixture 4 in the recirculation loop 6 will dry said surfaces which carry said gasoline 50 in the liquid state, so that said gasoline 50 joins said gas mixture 4 in the vapor state.

[0121] As shown in figure 2 , the withdrawal of homogeneous gas mixture 4 consisting of air 49 and gasoline 50 symbolized on said figure 2 by the letters "AF" is operated via the mixing withdrawal conduit 11 which opens into the mixing chamber 5 and more precisely, into the recirculation loop 6 which forms the internal cavity of the mixing chamber 5.

[0122] We notice in figures 1 to 5 and in figure 6 that the upper reversal termination 15 of the external coaxial conduit 14 is partly enveloped by a withdrawal ring 23, the interior of which is connected to the interior of the external coaxial conduit 14 by radial withdrawal orifices 24, the mixing withdrawal conduit 11 being connected to the mixing enclosure 5 by means of said ring 23 and said orifices 24.

[0123] As can be seen in figures 1 to 4 and in figure 6 , the position and orientation of the radial withdrawal orifices 24 are designed to disturb as little as possible the flow of the homogeneous gas mixture 4 in the external coaxial conduit 14 and more precisely, in the upper reversal termination 15 of the external coaxial conduit 14.

[0124] Thus, when homogeneous gas mixture 4 is drawn from the mixing chamber 5 by the stratification injector 20, said mixture 4 is perfectly homogeneous, and is exclusively made up of air 49 and gasoline 50 in a proportion of fourteen grams of air 49 per gram of gasoline 50.

[0125] To obtain precisely such a proportion of air 49 and gasoline 50 requires knowing the mass flow rate of air 49 admitted into the mixing chamber 5, in order to be able to introduce into said air 49 the correct quantity of gasoline 50 via the liquid injection nozzle 9.

[0126] This is why the forced recirculation mixer 1 according to the invention cooperates, according to the embodiment taken here to illustrate its operation, with a gas mass flow meter 46 which can be a pressure reducing device, a Pitot tube, a ludion, a cup, a propeller or a turbine, a vane, an ionic, ultrasonic, electromagnetic, a Coriolis effect, a Karman vortex or a vortex effect, a hot wire or film, a thermal mass, or generally, of any type known to those skilled in the art.

[0127] Said flow meter 46 returns the actual mass flow rate of air 49 admitted into the mixing chamber 5 to the computer 45 which is symbolized in figure 1 by the letters “ECU”, said calculator 45 being able to control the piston liquid pump 32 accordingly.

[0128] As seen in figures 1 , 3 , 4 And 6, the double-acting pump piston 33 of the piston liquid pump 32 is here moved in translation in the pump cylinder 35 with which it cooperates by a rotary electric actuator motor 39 secured to the pump casing 42.

[0129] As shown by the figures 3 And 4 , the rotary electric actuator motor 39 can rotate in either direction to drive in rotation driving transmission means 40 which are integral in translation with the pump casing 42 and which are here formed of a worm screw 47 which drives in rotation a worm wheel 43 provided with a wheel thread 56.

[0130] As we can clearly see in figures 3 And 4 , the wheel thread 56 cooperates with a piston thread 57 which is integral with the pump piston 33 and which forms driven transmission means 41.

[0131] By rotating on itself under the action of the worm screw 47, the worm wheel 43 screws or unscrews the female wheel thread 56 around the male piston thread 57, which has the effect of moving the double-acting pump piston 33 in translation in the pump cylinder 35.

[0132] There figure 3 shows that when the rotary electric actuator motor 39 turns the worm screw 47 clockwise, the pump piston 33 descends and expels the gasoline 50 contained in the lower pump chamber 36 out of said chamber 36 via the discharge valve 38 of the latter, while the upper pump chamber 36 sucks gasoline 50 via its inlet valve 37.

[0133] There figure 4shows what happens when the rotary electric actuator motor 39 turns the worm screw 47 counterclockwise. In this case, the pump piston 33 rises and expels the gasoline 50 contained in the upper pump chamber 36 from said chamber 36 via the delivery valve 38 of the latter, while the lower pump chamber 36 sucks gasoline 50 via its inlet valve 37

[0134] We notice in figure 6 that the piston thread 57 is locked in rotation in the pump casing 42 by a hexagonal head 58 which cooperates with a complementary extrusion shape arranged in said casing 42.

[0135] We also notice in figures 1 , 3 , 4 And 6 that while rotating around its longitudinal axis, the worm wheel 43 is axially supported in the pump casing 42 by means of ball bearings 59 known per se.

[0136] Finally, we notice in figures 1 , 3 , 4 And 6 that any axial play between the worm wheel 43 and the pump casing 42 is eliminated by an axial play elimination spring 60 interposed, according to this example, between said casing 42 and the upper ball thrust bearing 59.

[0137] In figure 1 and in figures 3 to 6 , we have shown the rotary electric actuator motor 39 which is here and according to this example a so-called brushless motor 39 which integrates a “Hall effect” encoder generating thirty pulses per revolution of said motor 39.

[0138] We notice, particularly in figures 1 , 3 , 4 And 6 , that the interior of the pump cylinder 35 has an initialization stop 61 in contact with which the pump piston 33 can come so that the computer 45 can count the pulses generated by the “Hall effect” encoder from this reference.

[0139] Thus, if the worm wheel 43 has thirty teeth, if the pitch of the wheel thread 56 and the piston thread 57 is one millimeter, and taking into account the thirty pulses generated by the “Hall effect” encoder at each revolution of the rotary electric actuator motor 39, one pulse from the “Hall effect” encoder corresponds to a displacement of the pump piston 33 of approximately one micrometer.

[0140] Since the ratio between the displacement of the pump piston 33 and the quantity of gasoline 50 expelled from the corresponding pump chamber 36 is known to the computer 45, the latter can precisely control the rotation of the rotary electric actuator motor 39 so as to generate a mass flow rate of gasoline 50 to be expelled via the liquid injection nozzle 9 equal to one fourteenth of the mass flow rate of air 49 returned to said computer 45 by the gas mass flow meter 46.

[0141] As can easily be deduced from the above, the forced recirculation mixer 1 according to the invention makes it possible to produce a homogeneous gas mixture 4 formed here of air 49 and gasoline 50 in a proportion of fourteen grams of air 49 per gram of gasoline 50.

[0142] For this, the forced recirculation mixer 1 does not require any high-pressure fuel pump, the pressure of a few bars usually delivered by the fuel pumps 53 equipping the most widespread multipoint injection systems in automobiles being, for example, sufficient to supply the piston liquid pump 32. Indeed, it is the piston liquid pump 32 itself which is responsible for raising the pressure of the gasoline 50 to more than forty bars necessary for the introduction of said gasoline 50 into the mixing chamber 5 via the liquid injection nozzle 9.

[0143] To achieve the desired result, the forced recirculation mixer 1 according to the invention also does not require a high-precision injector, the injected quantity of which remains uncertain in all cases, particularly at very low flow rates. It will also be noted that the particular configuration of the forced recirculation mixer 1 does not require atomizing the gasoline 50 into fine droplets to ensure its complete vaporization. Indeed, said vaporization can be carried out a posteriori in the recirculation loop 6, without damaging the average richness in gasoline 50 of the homogeneous gas mixture 4.

[0144] As can be deduced from the figures and from the present description of operation of the forced recirculation mixer 1, the piston liquid pump 32 simultaneously ensures the injection and the measurement of the flow rate of the gasoline 50 introduced into the mixing chamber 5 via the liquid injection nozzle 9. Said piston liquid pump 32 therefore avoids having to use a gasoline flow meter 50 to form the homogeneous gas mixture 4 with the due proportion of air 49 and gasoline 50.

[0145] It can be seen that if the diameter of the pump piston 33 is twelve millimeters, this with a worm wheel 43 of thirty teeth, a wheel thread pitch 56 and piston thread pitch 57 of one millimeter, and with thirty pulses generated by the "Hall effect" encoder at each revolution of the rotary electric actuator motor 39, one pulse from the "Hall effect" encoder corresponds to approximately zero point eight milligrams of gasoline 50 injected into the mixing chamber 5 via the liquid injection nozzle 9.

[0146] If the wheel thread pitch 56 is halved, the amount of gasoline 50 injected per pulse of the "Hall effect" encoder is half as small.

[0147] It will be noted that the total number of pulses generated by the “Hall effect” encoder over the entire stroke of the pump piston 33 therefore corresponds to a certain quantity of gasoline 50, determined with great precision.

[0148] As a result, the accuracy of the quantity of gasoline 50 introduced into the brewing chamber 5 via the liquid injection nozzle 9 between two pulses of the “Hall effect” encoder is on average very high.

[0149] As the mixing chamber 5 dilutes said quantity of gasoline 50 in a large quantity of homogeneous gas mixture 4 over a relatively long time, the richness of the homogeneous gas mixture 4 drawn off by the stratification injector 20 is very precise, which promotes control in all circumstances of the operation of the ignition pre-chamber with valve 21 according to patent FR 3 061 743.

[0150] It is noted that the pump piston 33 being double-acting, its maximum forward speed may, for example if its diameter is twelve millimeters, not exceed three or four millimeters per second to supply the ignition pre-chambers with valve 21 of a supercharged thermal engine 51 with a two-liter cylinder capacity operating at maximum power.

[0151] This millimetric speed makes it possible to equip said piston 33 with a perfectly watertight piston seal 19 whose service life will be long despite the fact that it operates in 50 gasoline which has no particular lubricating properties.

[0152] Indeed, the piston seal 19 may for example be composite and comprise a ring made of PTFE loaded with anti-friction particles, said ring being held in contact with the pump cylinder 35. Such a piston seal 19 is particularly suited to the operating conditions which have just been described and may last at least as long as the heat engine 51 with which it cooperates in supplying the ignition pre-chamber with valve 21 with homogeneous gas mixture 4 via the stratification injector 20.

[0153] It will be noted that according to the exemplary embodiment of the forced recirculation mixer 1 according to the invention which has just been described, the computer 45 advantageously compensates for the losses in average gasoline flow rate 50 during changes in direction of the double-acting pump piston 33 in the pump cylinder 35.

[0154] Indeed, at the point of reversal of said piston 33, the rotary electric actuator motor 39 must take up certain clearances such as that found between the worm 47 and the worm wheel 43, or compensate for the deformation of the piston seal 19 in its groove when changing the direction of the pressure difference to which said seal 19 is subjected.

[0155] The computer 45 can carry out this adjustment by measuring the intensity of the electric current required by the rotary electric actuator motor 39 to move, said intensity making it possible to detect the moment when the pump piston 33 is again facing a pressure of at least forty bars.

[0156] The computer 45 can also integrate data on the necessary adjustment to be made at the point of return of the pump piston 33, this data resulting from bench tests carried out prior to commissioning the forced recirculation mixer 1 according to the invention.

[0157] Thus, taking into account the time allocated to the recharging operation of the pump piston 33, the computer 45 can reconstitute the average flow rate necessary to obtain the homogeneous gas mixture 4 according to the desired air 49 to gasoline 50 ratio, knowing that the temporary variation in richness seen by the stratification injector 20 is negligible given the significant amount of homogeneous gas mixture 4 contained in the mixing chamber 5.

[0158] In figures 7 to 10, an alternative embodiment of the forced recirculation mixer 1 according to the invention has been shown, according to which the means for introducing liquid in a controlled quantity 10 no longer consist of a piston liquid pump 32 as has just been described, but of an impulse pump 63 housed in a pump casing 42.

[0159] According to the exemplary embodiment of the forced recirculation mixer 1 according to the invention shown in figures 7 to 9 , the pulse pump 63 comprises a single-acting pulse pump piston 64 which, under the action of a pump solenoid actuator 65, can move in translation in a pulse pump cylinder 67.

[0160] We will also assume here that the gas to be mixed 3 is atmospheric air 49 while the vaporizable liquid 2 is gasoline 50 as commonly consumed by automobiles.

[0161] The pulse pump piston 64 forms with the pulse pump cylinder 67 a pulse pump chamber 68 of variable volume into which the gasoline 50 can be introduced via a pulse pump inlet valve 69, and from which said gasoline 50 can be expelled towards the liquid injection nozzle 9 via a pulse pump discharge valve 70.

[0162] It is noted that the discharge valve of the pulse pump 70 can be highly calibrated - to several bars - so that if the pressure prevailing in the mixing chamber 5 is lower than that prevailing in the gasoline circuit 50 located upstream of the pulse pump 63, the mixing chamber 5 does not fill with gasoline 50 undesirably.

[0163] To inject the gasoline 50 into the mixing chamber 5, the computer 45 supplies electric current to the solenoid coil 95 of the pump solenoid actuator 65. This has the effect of pushing the pulse pump piston 64 towards the pulse pump chamber 68, said piston 64 expelling the corresponding quantity of gasoline 50 from said chamber 68 via the pulse pump discharge valve 70 and the liquid injection nozzle 9.

[0164] Once this is done, the computer 45 stops supplying the solenoid coil 95 with electric current so that a pump piston return spring 66 returns the pulse pump piston 64 to bottom dead center and the pulse pump chamber 68 again admits gasoline 50 via its pulse pump inlet valve 69.

[0165] It is noted that the pump piston return spring 66 is not necessary if the fuel supply pressure 50 which prevails upstream of the pulse pump inlet valve 69 is sufficient to push the pulse pump piston 64 back to bottom dead center within the allotted time.

[0166] In figures 7 to 9 , we notice the presence of a nozzle accumulator 80 interposed between the pulse pump 63 and the liquid injection nozzle 9.

[0167] The nozzle accumulator 80 makes it possible to provide a liquid injection nozzle 9 leaving only a small section for the passage of the gasoline 50 which promotes fine atomization of said gasoline 50 at the outlet of said nozzle 9 in the mixing enclosure 5.

[0168] The nozzle accumulator 80 also makes it possible to clip the pressure peaks occurring at the outlet of the pulse pump discharge valve 70, which avoids oversizing the solenoid coil 95 to counter said peaks.

[0169] Furthermore, the nozzle accumulator 80 reduces the amplitude of the variations in the flow rate of gasoline 50 vaporized in the mixing chamber 5 by the liquid injection nozzle 9, which leads to better homogeneity of the homogeneous gas mixture 4 formed in said chamber 5.

[0170] According to the non-limiting example shown in figures 7 to 8 , the nozzle accumulator 80 comprises a nozzle accumulator piston 81 which forms, with an accumulator cylinder 82, an accumulator chamber 83, said piston 81 being pushed towards said chamber 83 by an accumulator spring 84 while the liquid injection nozzle 9 is integral with said piston 81 and passes through the latter from side to side in the direction of its length.

[0171] In figures 8 And 9, it is noted that means for adjusting the solenoid stroke 96 make it possible to adjust the effective stroke of the pulse pump piston 64 and therefore to adjust the displacement of the pulse pump 63.

[0172] It is easily deduced from the above that the flow rate of gasoline 50 injected into the mixing chamber 5 by the pulse pump 63 is the product of the cylinder capacity of said pump 63 by its volumetric efficiency by its actuation frequency.

[0173] For example, if the displacement of said pump 63 is thirteen cubic millimeters, if the volumetric efficiency of said pump 63 is seventy percent, and its actuation frequency is thirty Hertz, then the flow rate of said pump 63 is two hundred seventy-three cubic millimeters per second.

[0174] In order for the computer 45 to regulate the effective flow rate of the pulse pump 63 necessary for the formation in the mixing chamber 5 of the homogeneous gas mixture 4 according to the desired air 49 to gasoline 50 ratio, as can be seen in figures 7 to 9 , the forced recirculation mixer 1 comprises a vaporizable liquid flow meter 71 which returns to said computer 45 the actual mass flow rate of gasoline 50 injected by the liquid injection nozzle 9 into the mixing chamber 5.

[0175] Thanks to the vaporizable liquid flow meter 71, the computer implements a software control loop of the “PID regulator” type, known per se.

[0176] In fact, the gas mass flow meter 46 returns to the computer 45 the actual mass flow rate of air 49 entering the mixing chamber 5, from which naturally follows the gasoline flow rate setpoint 50 to be introduced into said chamber 5 by the pulse pump 63 taking into account the desired air 49 to gasoline 50 ratio.

[0177] The gasoline flow rate 50 therefore forms the value set by the PID regulator, said flow rate being able to oscillate more or less around the set value assigned to it provided that the actual value of said flow rate is close to said set value when it is averaged over a few seconds.

[0178] In fact, the forced circulation by the mixing turbine 13 of the homogeneous gas mixture 4 in the mixing chamber 5 homogenizes said mixture 4 despite variations in the flow rate of gasoline 50 around the set value.

[0179] To regulate the fuel flow 50 upwards or downwards, the computer 45 can modulate the frequency and / or the activation power of the pump solenoid actuator 65 of the pulse pump 63.

[0180] According to the non-limiting example embodiment of the forced recirculation mixer 1 according to the invention shown in figures 7 to 9 , the vaporizable liquid flow meter 71 comprises in particular a flow meter piston 72 which can move in a sealed manner in a flow meter cylinder 73 so as to form on the one hand, an upstream flow meter chamber 75 connected to the fuel pump 53 of the heat engine 51, and on the other hand, a downstream flow meter chamber 76 which is connected to the inlet of the pulse pump 63.

[0181] We note, particularly in figures 7 And 8 , that the flow meter piston 72 has at each of its ends a sealed flow meter piston extension 101 opening into the open air.

[0182] The sealed flow meter piston extensions 101 ensure that for the same movement of the flow meter piston 72, the volume of gasoline 50 admitted or discharged by the upstream flow meter chamber 75 is identical to that simultaneously admitted or discharged by the downstream flow meter chamber 76. Thus, the flow of gasoline 50 delivered by the fuel pump 53 is in no way disturbed by the back and forth movements made by the flow meter piston 72 in the flow meter cylinder 73, whatever the speed of said back and forth movements.

[0183] The position of the flow meter piston 72 in the flow meter cylinder 73 is transmitted to the computer 45 by a position sensor 74 which, in this case, is an absolute linear encoder such as those marketed by the company “Posic”.

[0184] The encoder reads a target strip 100 which is carried by a guided strip holder drawer 97, the latter being able to move in longitudinal translation in a drawer guide rail 98 in which it is housed with little play on the one hand, and in the extension of the flow meter piston 72 on the other hand.

[0185] It is noted that the guided slide-holder 97 is made integral in translation with the flowmeter piston 72 by a coupling magnet 99, the latter being permanently attracted by the sealed flowmeter piston extension 101 which is positioned on the side of the target slide 100.

[0186] In figures 7 to 9 , we notice the flow meter piston return spring 78 which tends to move the flow meter piston 72 towards the upstream flow meter chamber 75.

[0187] It is easily deduced from the diagram of the figure 7 the working principle of the vaporizable liquid flow meter 71.

[0188] Indeed, to determine the mass flow rate of gasoline 50 introduced into the mixing chamber 5 by the pulse pump 63, the computer 45 recovers on the one hand and via the position sensor 74 the distance traveled per unit of time by the flow meter piston 72, and on the other hand by means of a temperature sensor 103 placed at the level of the downstream flow meter chamber 76, the temperature of said gasoline 50.

[0189] For example, if the effective section of the flow meter piston 72 is one hundred and forty square millimeters, when the latter moves one millimeter per second, the volume flow rate of gasoline 50 introduced into the mixing chamber 5 by the pulse pump 63 is one hundred and forty cubic millimeters per second.

[0190] To calculate the mass flow rate of gasoline 50 introduced into the mixing chamber 5, the density at twenty degrees Celsius and the coefficient of thermal expansion of said gasoline 50 being known because they are provided by the computer (not shown) of the thermal engine 51, the computer 45 only has to multiply the density of said gasoline 50 by its volume flow rate.

[0191] For greater precision, a pressure sensor 102 may optionally be provided at the downstream chamber of flow meter 76, to allow the computer 45 to integrate the compressibility of the gasoline 50 into its calculation of the density of said gasoline 50.

[0192] When the flow meter piston 72 reaches the end of its reading stroke, that is to say when the volume of the downstream flow meter chamber 76 reaches its predetermined minimum value, the flow meter piston return valve 72 opens and connects said downstream chamber 76 with the upstream flow meter chamber 75, which has the effect of transferring gasoline 50 contained in the upstream flow meter chamber 75 into the downstream flow meter chamber 76.

[0193] This transfer of gasoline 50 results from the force exerted by the flow meter piston return spring 78 on the flow meter piston 72, said force having the effect of moving the latter in the direction of the upstream flow meter chamber 75.

[0194] During said transfer of gasoline 50 which can last of the order of a hundred milliseconds, the measurement of the volume flow rate of gasoline 50 is momentarily interrupted. However, the total measurement error is very small because the computer 45 can reconstruct the flow rate of gasoline 50 during the interruption of the measurement by taking the average between the flow rate of gasoline 50 recorded just before the opening of the flow meter piston return valve 72 and that recorded just after the closing of said valve 72.

[0195] It should be noted in this respect that the return operation of the flow meter piston 72 which has just been described only occurs rarely, for example every ten minutes when the thermal engine 51 is operating at idle, and every four seconds when said engine 51 is operating at full power.

[0196] It is noted that the flowmeter piston return valve 72 may advantageously be of the “normally open” type as shown in figures 7 , 9 And 10 , so that when the engine 51 is permanently stopped, the thermal expansion or contraction of the gasoline 50 contained in the internal circuits and volumes of the forced recirculation mixer 1 according to the invention can never result in untimely injections of said gasoline 50 into the mixing chamber 5 via the pulse pump 63 and the liquid injection nozzle 9.

[0197] In figure 10 , the flowmeter piston return valve 72 has been shown in more detail, which comprises a swivelling sealing plate 85 which can be held pressed against a valve orifice 86 via a valve seal 87 by a valve solenoid actuator 88, the latter pushing on the swivelling sealing plate 85 via a resilient connection 89 consisting of a closing holding spring 93 whose maximum length is limited by a stop pin 94.

[0198] In figure 7 , certain accessories useful for the proper functioning of the forced recirculation mixer 1 according to the invention have also been shown in the context of the implementation of the ignition pre-chamber with valve 21 which is the subject of patent FR 3 061 743, on an automobile thermal engine 51.

[0199] For example, we note the sealed non-return valve at the compressor outlet 90 which makes it possible to keep the mixing chamber 5 under pressure when the thermal engine 51 is stopped for a few seconds to a few minutes, said valve 90 being very useful when the discharge valves of the compressor 18 are not perfectly sealed.

[0200] We also note the canister discharge solenoid valve 91 which allows the mixing chamber 5 to be gradually depressurized when the heat engine 51 is stopped and cools down. When said solenoid valve 91 opens, the gasoline 50 in the vapor state which forms the homogeneous gas mixture 4 contained in said chamber 5 is transferred into a canister 92 known per se, such a canister 92 equipping the majority of modern automobiles.

[0201] It will be noted that the examples of embodiment of the forced recirculation mixer 1 according to the invention which have just been described are non-limiting.

[0202] Indeed, the heat engine with its forced recirculation mixer 1 according to the invention can be applied to other fields than that of heat engines, such as chemistry, industrial processes or any devices in any field whatsoever which require the in situ production of a mixture which is homogeneous and / or precisely dosed, consisting of at least one gas and at least one liquid.

[0203] The possibilities of the forced recirculation mixer 1 according to the invention are not limited to the applications which have just been described and it should also be understood that the preceding description has been given only by way of example and that it in no way limits the scope of said invention which is defined in the claims.

Claims

1. Heat engine comprising a forced recirculation mixer (1) designed to mix at least one vapourisable liquid (2) with at least one gas to be mixed (3) so as to form a homogeneous gas mixture (4) which is injected in the form of a pilot charge (55) into an ignition prechamber by a stratification injector (20), characterised in that said mixer comprises: • at least one mixing enclosure (5) the internal cavity of which forms a recirculation loop (6) in which the homogeneous gas mixture (4) can continuously flow, the start and the end of the recirculation loop (6) being merged; • at least one gas inlet duct (7) which opens directly or indirectly into the mixing enclosure (5) and through which the gas to be mixed (3) is introduced into the recirculation loop (6) by means (8)for introducing gas in a known quantity; • at least one liquid injection nozzle (9) which opens directly or indirectly into the mixing enclosure (5) to introduce the vapourisable liquid (2) into the recirculation loop (6), said nozzle (9) being supplied by means (10) for introducing liquid in controlled quantity, the flow rate of vapourisable liquid (2) of which is controlled by a computer (45), said vapourisable liquid (2) forming, with the gas (3) to be mixed, the homogeneous gas mixture (4); • at least one mixture withdrawal duct (11) that opens directly or indirectly into the mixing enclosure (5) and through which the homogeneous gas mixture (4) can be withdrawn from the recirculation loop (6) by gas withdrawal means (12); • at least one mixing turbine (13) which is set in motion by a turbine motor (28) and which is positioned in the recirculation loop (6), said turbine (13) forcing the homogeneous gas mixture (4) to flow in said loop (6).

2. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that the mixing enclosure (5) comprises at least one outer coaxial duct (14), each end of which is closed by a reversal termination (15), while at least one inner coaxial duct (16) is housed in the outer coaxial duct (14) and that a space is left for the homogeneous gas mixture (4) to flow, on the one hand, between each reversal termination (15) and the inner coaxial duct (16) and, on the other hand, between the inner face of the outer coaxial duct (14) and the outer face of the inner coaxial duct (16), the flow direction of the homogeneous gas mixture (4) in the outer coaxial duct (14) being opposite to the flow direction of said mixture (4) in the inner coaxial duct (16).

3. Heat engine comprising a forced recirculation mixer according to claim 2, characterised in that the mixing turbine (13) is entirely or partly housed in one of the reversal terminations (15), the homogeneous gas mixture (4) being sucked by the centre of said turbine (13) via the internal coaxial duct (16) before being discharged at the periphery of said turbine (13) via the space left between the internal face of the external coaxial duct (14) and the external face of the internal coaxial duct (16).

4. Heat engine comprising a forced recirculation mixer according to claim 3, characterised in that the reversal termination (15) that houses the mixing turbine (13) has a recessed hemi-toroidal shape while blades (17) that the mixing turbine (13) comprises have a complementary projecting hemi-toroidal shape, a small clearance being left between said termination (15) and said blades (17).

5. Heat engine comprising a forced recirculation mixer according to claim 2, characterised in that the gas inlet duct (7) passes through one of the reversal terminations (15) to open into the inner coaxial duct (16).

6. Heat engine comprising a forced recirculation mixer according to claim 5, characterised in that the reversal termination (15) through which the gas inlet duct (7) passes has a semi-toroidal shape in which said duct (7) emerges.

7. Heat engine comprising a forced recirculation mixer according to claim 5, characterised in that the liquid injection nozzle (9) opens inside the gas inlet duct (7), or at the outlet thereof.

8. Heat engine comprising a forced recirculation mixer according to claim 2, characterised in that the inner coaxial duct (16) is held in position in the outer coaxial duct (14) by at least one mixing blade (22) which radially connects said inner coaxial duct(16) to said outer coaxial duct(14).

9. Heat engine comprising a forced recirculation mixer according to claim 2, characterised in that the outer coaxial duct (14) or any one of its reversal terminations (15) is entirely or partially enveloped by a withdrawal ring (23), the inside of the latter being connected to the inside of the outer coaxial duct (14) by at least one radial withdrawal orifice (24), the mixture withdrawal duct (11) being connected to the mixing enclosure (5) by means of said ring (23) and said orifice (24).

10. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that the mixing enclosure (5) comprise heating or cooling means (25).

11. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that the turbine motor (28) is an electric motor (29) which comprises, on the one hand, a rotor (30) which is rotationally fixed to the mixing turbine (13) and which is enclosed in the mixing enclosure (5), and, on the other hand, a stator (31) which is placed outside said chamber (5), magnetic fields produced by said stator (31) being able to pass through the wall of the mixing enclosure (5) in order to rotate the rotor (30).

12. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that the means (10) for introducing liquid in controlled quantity consist of a piston liquid pump (32) which comprises a pump casing (42), said pump (32) also comprising at least one single or double-acting pump piston (33) which, under the action of a piston actuator (34) cooperating with movement control means (44), can move in translation in a pump cylinder (35) to form at least one pump chamber (36) of variable volume into which the vapourisable liquid (2) can be introduced via an intake valve (37), and from which said liquid (2) can be expelled towards the liquid injection nozzle (9) via a discharge valve (38).

13. Heat engine comprising a forced recirculation mixer according to claim 12, characterised in that the piston actuator (34) consists of a rotary electric actuator motor (39) secured to the pump casing (42), said motor (39) being able to rotate in either direction to drive in rotation driving transmission means (40) which are secured in translation to the pump casing (42) and which cooperate with driven transmission means (41) which are secured in translation to the pump piston (33), said driving transmission means (40) reacting with said casing (42) to move said driven transmission means (41) in longitudinal translation.

14. Heat engine comprising a forced recirculation mixer according to claim 13, characterised in that the driving transmission means (40) are formed of a worm (47) which drives in rotation a worm wheel (43) which has a wheel thread (56), while the driven transmission means (41) consist of a piston thread (57) which cooperates with the wheel thread (56).

15. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that a gas mass flow meter (46) measures, directly or indirectly, the mass flow rate of the gas to be mixed (3) which flows in the gas inlet duct(7) and / or the mass flow rate of the homogeneous gas mixture (4) which flows in the mixture withdrawal duct (11).

16. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that the means (10) for introducing liquid in controlled are constituted of an impulse pump (63) which comprises a single or double-acting impulse pump piston (64) which, under the action of a pump solenoid actuator (65), can move in translation in an impulse pump cylinder (67) with which it forms at least one impulse pump chamber (68) of variable volume in which the vapourisable liquid (2) can be introduced via an impulse pump intake valve (69), and from which said liquid (2) can be expelled towards the liquid injection nozzle (9) via an impulse pump discharge valve (70).

17. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that the volume and / or mass flow rate of vapourisable liquid (2) is returned to the computer (45) by a vapourisable liquid flow meter (71) placed upstream or downstream of the means (10) for introducing liquid in controlled quantity.

18. Heat engine comprising a forced recirculation mixer according to claim 17, characterized in that the vapourisable liquid flowmeter (71) consists of a flowmeter piston (72) which can move in a sealed manner in a flowmeter cylinder (73) so as to form, on the one hand, an upstream flowmeter chamber (75) which is directly or indirectly connected to a pressure source (77), and, on the other hand, a downstream flowmeter chamber (76) which is directly or indirectly connected to the liquid injection nozzle (9), the position of said piston (72) in said cylinder (73) being transmitted to the computer (45) by a position sensor (74), while a flowmeter piston return spring (78) tends to push back the flowmeter piston (72) towards the upstream flowmeter chamber (75).

19. Heat engine comprising a forced recirculation mixer according to claim 18, characterised in that the upstream flowmeter chamber (75) can be connected to the downstream flowmeter chamber (76) by a flowmeter piston return valve (72).

20. Heat engine comprising a forced recirculation mixer according to claim 19, characterised in that the flowmeter piston return valve (72) comprises a steerable sealing plate (85) which can be kept pressed against a valve orifice (86) by a valve solenoid actuator (88).

21. Heat engine comprising a forced recirculation mixer according to claim 1, characterised in that a nozzle accumulator (80) is interposed between the means (10) for introducing liquid in controlled quantity and the liquid injection nozzle (9).

22. Heat engine comprising a forced recirculation mixer according to claim 21, characterised in that the nozzle accumulator (80) comprises a nozzle accumulator piston (81) which forms, with an accumulator cylinder (82), an accumulator chamber (83), said piston (81) being pushed in the direction of said chamber (83) by an accumulator spring (84) while the liquid injection nozzle (9) is secured to said piston (81) and passes through the latter from one side to the other in the lengthwise direction.